Increase minimum task runtime per-sched cycle

Hackbench scores increased significantly

Signed-off-by: Tyler Nijmeh <tylernij@gmail.com>

README.md

@@ -79,8 +79,8 @@ This is more of a precaution than anything. Since the next few tunables will be
 ### kernel.sched_latency_ns: 10000000 (10ms)
 Set the default scheduling period to 10ms. If this value is set too low, the scheduler will switch contexts too often, spending more time internally than executing the waiting tasks.
 
-### kernel.sched_min_granularity_ns: 1000000 (1ms)
-Set the minimum task scheduling period to 1ms. With kernel.sched_latency_ns set to 1ms, this means that 10 tasks may execute within the 10ms scheduling period before we exceed it.
+### kernel.sched_min_granularity_ns: 2500000 (2.5ms)
+Set the minimum task scheduling period to 2.5ms. With kernel.sched_latency_ns set to 2.5ms, this means that 4 active tasks may execute within the 10ms scheduling period before we exceed it. Originally, this value was set to 1ms. After benchmarking using `hackbench -pl 8000`, it was determined that a higher value reduces hackbench times significantly. The tradeoff is scheduling latency.
 
 ### kernel.sched_migration_cost_ns: 500000 (0.5ms) --> 1000000 (1ms)
 Increase the time that a task is considered to be cache hot. According to RedHat, increasing this tunable reduces the number of task migrations. This should reduce time spent balancing tasks and increase per-task performance.

system/bin/ktweak

@@ -115,7 +115,7 @@ write /proc/sys/kernel/sched_group_downmigrate 50
 write /proc/sys/kernel/sched_group_upmigrate 80
 write /proc/sys/kernel/sched_tunable_scaling 0
 write /proc/sys/kernel/sched_latency_ns 10000000
-write /proc/sys/kernel/sched_min_granularity_ns 1000000
+write /proc/sys/kernel/sched_min_granularity_ns 2500000
 write /proc/sys/kernel/sched_migration_cost_ns 1000000
 write /proc/sys/kernel/sched_min_task_util_for_boost 35
 write /proc/sys/kernel/sched_min_task_util_for_colocation 25